Rock Identifier
Polished Ocean Jasper (Orbicular jasper (microcrystalline quartz, SiO₂)) — mineral
mineral

Polished Ocean Jasper

Orbicular jasper (microcrystalline quartz, SiO₂)

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque red, orange, cream, gray, and brown orbicular patterns; vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage. The pictured material is polished and shaped, with spherical quartz/chalcedony-rich inclusions.

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Physical properties

Hardness about 6.5–7 Mohs; opaque red, orange, cream, gray, and brown orbicular patterns; vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage. The pictured material is polished and shaped, with spherical quartz/chalcedony-rich inclusions.

Formation & geological history

Forms when silica-rich volcanic fluids or groundwater fill cavities and fractures in altered volcanic rock, producing concentric orbicules and brecciation. Classic Madagascar ocean jasper formed in Mesozoic volcanic terrains, generally tens to hundreds of millions of years old.

Uses & applications

Used for cabochons, spheres, carvings, beads, and display specimens; occasionally used as ornamental stone. Value depends strongly on vivid orbicules, color contrast, polish, and provenance.

Geological facts

“Ocean jasper” is a trade name, not a single officially defined mineral species; much marketed material comes from remote coastal localities near Marovato, Madagascar.

Field identification & locations

Identify it by its polished red-orange groundmass and abundant circular orbicules, often with quartz/chalcedony veins; glass lacks natural pattern variation and is usually harder to distinguish by magnification. Commonly found in Madagascar, with similar orbicular jasper from elsewhere.